Odorant or flavoring thiazolyl disulphides

ABSTRACT

Novel odorant and/or flavoring substances such as 2-phenylethyl-ethyl-disulphide, process for preparing such disulphides and odorant and flavoring products containing the sulphides are disclosed.

FIELD OF THE INVENTION

This invention relates to novel disulphides and to the fields ofolfactory and flavoring products.

SUMMARY OF THE INVENTION

The novel disulphides of this invention have the formula:

    R.sub.1 --(Y).sub.n --S--S--R.sub.2                        (I)

wherein R₁ represents an optionally substituted phenyl or furyl group,or an optionally substituted monocyclic group containing nitrogen and/orsulphur and, if desired, also oxygen as the hetero atom, R₂ represents alower alkyl or lower alkenyl group, Y represents an optionally mono- ordi-substituted methylene group and n stands for 0-5 with the provisothat n stands for 2-5 when R₁ represents a phenyl or furyl group.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the process provided by the present invention, thedisulphides of formula I hereinbefore are manufactured by reacting acompound of the general formula

    ______________________________________                                                ##STR1##             (II)                                             or                                                                                    ##STR2##             (III)                                            or                                                                                    ##STR3##             (IV)                                             or                                                                                    ##STR4##             (V)                                              or                                                                                    ##STR5##             (VI)                                             or                                                                                    ##STR6##             (VII)                                            ______________________________________                                    

with a mercaptan of the general formula

    A--SH                                                      (VIII)

, whereby in the one reaction component A represents a group R₁ (Y)_(n)and in the other reaction component A represents a group R₂, Y and nhave the significance given earlier except that n should only stand for1-4 in formulae II, III and V, R represents a lower alkyl group, Xrepresents the diacyl residue of an aliphatic or aromatic dicarboxylicacid and Z.sup.⊖ represents an anion.

As heterocyclic groups containing nitrogen and/or sulphur and, ifdesired, also oxygen as the hetero atom there come into consideration,in particular, 5-membered or 6-membered heterocyclic groups whichcontain one or more nitrogen atoms and/or one or more sulphur atoms.Examples of heterocycles forming a basis for these heterocyclic groupsinclude pyrrole, pyridine, pyrazine, imidazole, pyrazole, pyrimidine,thiophene, thiazole, isothiazole, oxazole, triazole, etc, whichheterocycles can be substituted (e.g. lower alkyl substituted).

The position at which the heterocyclic ring is bound with the rest ofthe molecule is not critical. The lower alkyl and lower alkenyl groupsdenoted by R₂ (or R as the case may be) are especially straight-chain orbranched-chain groups containing from 1 to 6 carbon atoms (e.g. methyl,ethyl, propyl, isopropyl, butyl, sec.butyl, isobutyl, amyl, hexyl, etc).

Y represents an optionally mono- or di-substituted methylene group.Indeed, in addition to the unsubstituted methylene group (--CH₂ --), Yrepresents, in particular, a group of the formulae

    --CHR°--,or--CR°R°°--

wherein R° and R°° represent lower alkyl or lower alkenyl groups.

The reaction of a compound of formula II with a mercaptan of formulaVIII can be carried out according to methods known per se; for example:in accordance with Mukajyama et al, Tetrahedron Letters (1968), 5907 orBoekelheide et al, Tetrahedron Letters (1970), 1203.

The reaction is conveniently carried out in the presence of a base.Especially suitable bases are weak inorganic bases (e.g. ammonia, sodiumbicarbonate, sodium carbonate, etc) or inorganic bases (e.g. aliphaticor aromatic amines). An especially preferred amine isN,N-diisopropylethylamine. The reaction can be carried out in thepresence or absence of an organic solvent. Suitable solvents arehydrocarbons, especially aromatic hydrocarbons such as benzene, tolueneetc, halogenohydrocarbons such as chloroform, dichloromethane etc,ethers such as diethyl ether, alcohols such as alkanols (e.g. methanol,ethanol etc), esters such as alkanecarboxylic acid esters (e.g. ethylacetate). The temperature at which the reaction is carried out is notcritical. The reaction is conveniently carried out at a temperaturebetween about -20° C. and the reflux temperature of the reactionmixture, preferably at approximately 20°-70° C.

The isolation of the reaction product from the reaction mixture can becarried out according to methods known per se, for example, byconcentrating the reaction mixture, taking-up the residue in an organicsolvent (e.g. an optionally chlorinated hydrocarbon, an ether or anester etc), washing the organic phase with saturated aqueous sodiumbicarbonate solution, drying the organic phase and concentrating same.The desired disulphide of formula I can be obtained in pure form bydistillation or chromatography (e.g. on silica gel).

The compounds of formula II are conveniently prepared by reacting anazidocarboxylic acid ester of the general formula

    ROOC--N═N--COOR                                        (IX)

, wherein R has the significance given earlier, with a correspondingmercaptan of formula VIII. This reaction is preferably carried out inthe presence of catalytic amounts of a strong acid such as a mineralacid (e.g. sulphuric acid or hydrochloric acid) or p-toluenesulphonicacid. This reaction is conveniently carried out in an inert solvent.Suitable solvents include hydrocarbons (e.g. hexane), aromatichydrocarbons (e.g. benzene), halogenohydrocarbons (e.g. chloroform,dichloromethane etc) and ethers (e.g. diethyl ether). The temperature atwhich the reaction is carried out is not critical, but it convenientlylies between approximately -20° C. and 100° C. and preferably betweenroom temperature and the reflux temperature of the solvent. Athus-obtained compound of formula II can subsequently be isolatedaccording to methods known per se; for example, the methods describedearlier. A compound of formula II can, however, also be reacted in situwith a mercaptan of formula VIII.

The reaction of a compound of formula III with a mercaptan of formulaVIII can also be carried out according to methods known per se (Meijeret al, Rec.Trav.Chim. Pays Bas 93, 242 (1974)). In this case, themercaptan is conveniently used in the form of a metal salt (e.g. analkali metal salt and especially the lithium salt). Moreover, thereaction is conveniently carried out in a solvating medium (e.g. anether such as diethyl ether, dimethoxyethane etc, dimethylsulphoxide,dimethylformamide, hexamethylphosphortriamide etc). Dimethoxyethane is apreferred solvent. The temperature at which the reaction is carried outis not critical, but it conveniently lies between approximately -50° C.and approximately +50° C. and preferably between approximately -20° C.and room temperature. The desired disulphide of formula I obtained canbe purified and isolated according to methods known per se, for example,according to one of the methods described earlier.

The compounds of formula III can be prepared by reacting a correspondingmercaptan of formula VIII with dirhodan. A mercaptan of formula VIII isconveniently reacted with dirhodan which is conveniently generated insitu. The dirhodan is conveniently obtained from a heavy metal rhodanide(e.g. lead rhodanide) by treatment with an oxidising agent (e.g.bromine, etc) in an inert solvent. Suitable solvents are hydrocarbons(e.g. the aforementioned) or ethers (e.g. the aforementioned). Thetemperature at which the reaction between a mercaptan of formula VIIIand dirhodan is carried out is not critical, but it conveniently liesbetween about -30° C. and 80° C. and preferably between about -20° C.and room temperature. The thus-obtained compound of formula III can beisolated according to methods known per se; for example, theaforementioned methods. However, it can also be reacted in situ with amercaptan of formula VIII.

For the reaction of a compound of formula IV with a mercaptan of formulaVIII, a compound of formula IV is preferably first prepared in situ,namely from dimethyldithiobis(thioformate) of formula X (E. I. Stout etal., J.Org.Chem.39, 562 (1974)) and a corresponding mercaptan of formulaVIII: ##STR7##

In practice, dimethyldithiobis(thioformate) of formula X is placed, forexample, in an inert solvent at a temperature of, for example, -30° C.to room temperature, and the first mercaptan of formula VIII is addeddropwise thereto. This dropwise addition is accompanied by the additionof an equivalent of a base (e.g. an organic base such as an amine,preferably pyridine). Conveniently, the dissolved, neutralised mercaptanis added dropwise. After completion of the reaction (e.g. after 5 to 30minutes), the second mercaptan of formula VIII is added dropwisetogether with a second equivalent of base in the same manner asdescribed earlier and is thus brought to reaction with the compound offormula IV.

The reaction mixture is conveniently worked-up by extraction with anorganic solvent (e.g. one of the aforementioned solvents) or, in thecase of strongly volatile disulphides of formula I (e.g. those having aboiling point of ca 100° C. or above) by simple concentration. Thesubsequent purification can be carried out according to methods knownper se; for example, the methods mentioned earlier.

The reaction of a compound of formula V with a mercaptan of formula VIIIinvolves the oxidation of the mercaptan of formula VIII by the compoundof formula V (Reid, Organic Chemistry of bivalent Sulphur III, 372(1960)). The reaction is conveniently carried out in the presence of acatalyst. As the catalysts there come into consideration, in particular,bases; for example, inorganic bases such as alkali metal hydroxides(e.g. sodium hydroxide or potassium hydroxide) and metal hydrides (e.g.sodium hydride) or organic bases such as aliphatic or aromatic amines(e.g. triethylamine, pyridine, etc). The reaction can be carried out inthe presence or absence of a solvent. As the solvent, there may bementioned, for example, one of the aforementioned solvents. The reactionis conveniently carried out at an elevated temperature. The reaction canbe brought to completion by various measures; for example, by usingexcess of the compound of formula V, or, if desired, by continuousremoval of the disulphide of formula I, or by continuous removal of thefree mercaptan formed during the reaction, the removal being carriedout, for example, by distillation. The working-up of the reactionmixture is conveniently carried out by removal (e.g. filtration) orneutralisation of the catalyst with acid and concentration of the crudeproduct. Thereafter, the product can be recovered according to methodsknown per se.

The reaction of a compound of formula VI with a mercaptan of formulaVIII can be carried out according to methods known per se; see, forexample, K. S. Boustani et al, Tetrahedron Letters 1970 (3547); D. N.Harpp et al, Tetrahedron Letters 1970 (3551) or D. N. Harpp et al,J.Org.Chem. 36, 3828 (1971), Buchel et al, Chem. Ber. 100, 1248 (1967),Behforouz et al, J.Org.Chem. 34, 51(1969).

The diacyl residue of an aliphatic or aromatic dicarboxylic acid denotedby X in formula VI can be, for example, the residue of glutaric acid,succinic acid, phthalic acid, etc.

The reaction is conveniently carried out using approximately equivalentamounts of the mercaptan of formula VIII and the compound of formula VI.The reaction can be carried out in an inert organic solvent; forexample, a hydrocarbon such as an aliphatic hydrocarbon (e.g. hexane) oran aromatic hydrocarbon (e.g. benzene, etc), a chlorinated hydrocarbon(e.g. methylene chloride) and the like. The temperature at which thereaction is carried out is not critical, but it conveniently liesbetween about 0° C. and 150° C. and preferably between approximatelyroom temperature and the reflux temperature of the reaction mixture.

For the reaction of a compound of formula VII with a mercaptan offormula VIII, the former is preferably prepared in situ. For thispurpose, a -- preferably symmetric -- disulphide of the formulaA--S--S--A is first treated with an appropriate alkylating agent.Examples of the alkylating agents which may be used are tri(loweralkyl)oxonium salts such as, in particular, the tetrafluoroborate. Othersuitable salts can have, as the anion, the hexachloroantimonate,perchlorate, nitrate, arylsulphonate, alkylsulphonate or like anion. Inorder to obtain optimal yields, it is essential that the anion Z.sup.⊖of the alkylating agent used reacts less rapidly with the cation offormula VII than the anion A--S.sup.⊖ of the mercaptan VIII does.

The reaction is conveniently carried out in an inert solvent; forexample, an aliphatic or aromatic hydrocarbon such as hexane, heptane,benzene, toluene, etc, a chlorinated hydrocarbon such as chloroform,dichloromethane, etc, a nitro compound such as a nitroalkane (e.g.nitromethane, nitroethane, etc) or a sulphoxide (e.g.dimethylsulphoxide, etc). Preferred solvents are chlorinatedhydrocarbons such as dichloromethane or nitro compounds such asnitromethane. The molar ratio of disulphide to alkylating agentpreferably amounts to 1:1, but an excess of the disulphide can also beused.

The temperature at which the reaction is carried out is not critical,but it conveniently lies between about -20° C. and 50° C. The reactionmay, however, also be carried out at a higher or lower temperature. Whennitromethane is used as the solvent, a temperature of ca 0° C. ispreferred. The alkylated disulphide can be isolated, but it isconveniently reacted in situ with a mercaptan of formula VIII. Thelatter is preferably added to the dissolved salt as such or in the formof a salt (e.g. as the ammonium, alkali metal or alkaline earth metalsalt) in one of the aformentioned solvents, especially nitromethane. Thetemperature at which this procedure is carried out is conveniently thetemperature mentioned earlier.

The working-up of the reaction mixture can be carried out according tothe methods described earlier (e.g. chromatography and/or distillation).

The starting materials used in the various procedures described earlierare either known or can be prepared according to methods known per se.

The disulphides of formula I hereinbefore possess particular odorantand/or flavouring properties. In particular, the flavouring spectrum isvery broad. The present disulphides have fruity, spicy (e.g.mustard-like), vegetable-like (e.g. leek, celery, cauliflower, chive,onions, etc) and mushroom-like notes as well as cheese and meat notes.Of particular interest are the roast and meat notes.

The disulphides of formula I can accordingly be used, for example, forthe perfuming or flavouring of products such as cosmetics (soaps,salves, powders, etc), detergents, foodstuffs, luxury goods and drinks,the disulphides preferably not being used alone but rather in the formof compositions containing other odorant or flavouring substances.

The present invention is thus concerned, in another aspect, with odorantand/or flavouring compositions which contain as an essential odour -and/or flavour imparting ingredient a dipeptide of formula Ihereinbefore. Further, the present invention is concerned with a methodof imparting an odour and/or a flavour to materials, which methodcomprises applying to said materials or incorporating therein an odour -and/or flavour-imparting amount of a disulphide of formula Ihereinbefore or of an odorant and/or flavouring composition ashereinbefore defined.

Having regard to their natural notes, the present disulphides areespecially suitable for the modification of known compositions (e.g.those of the Chypre type or of flower notes).

The concentration of the disulphides of formula I in the composition ofthis invention can vary within wide limits depending on the purpose ofuse. For example, the concentration can be between about 0.001 wt. % inthe case of detergents, and about 10 wt. % in the case of alcoholicsolutions. In perfume bases or concentrates, the concentrations can, ofcourse, also be higher.

The disulphides of formula I can be used as flavouring substances, forexample, for the production or improvement, intensification, enhancementor modification of fruit, meat, or roast notes in foodstuffs (meat,synthetic meat products, sauces, broths, soups, vegetables, seasoningagents, snack foods, roast products such as coffee or cocoa, milkproducts such as cheese, curd, yoghurt, etc), in luxury goods (tobacco,crackers etc) and drinks (lemonades etc).

The pronounced flavour qualities of the present disulphides enable themto be used in low concentrations. A suitable range is ca 0.001 ppm -- 10ppm, preferably ca 0.1 ppm -- 10 ppm in the finished product (i.e. thearomatised foodstuff, luxury goods or drink).

The disulphides of formula I can be mixed with the ingredients used forflavouring substance compositions or can be added to such aromas in theusual manner. Among the aromas contemplated in accordance with thepresent invention there are to be understood flavouring substancecompositions which can be diluted or dispersed in edible materials in amanner known per se. They can be converted according to methods knownper se in the usual forms of use such as solutions, pastes or powders.The products can also be spray-dried, vacuum-dried or lyophilised.

As carrier materials, thickening agents, flavour-improvers, spices andauxiliary ingredients and the like which are suitable in the productionof such customary forms of use, there may be mentioned, for example:

Gum arabic, tragacanth, salts or brewers' yeast, alignates, carageens orsimilar absorbants; maltol, dienals, spice oleoresins, smoke flavours;cloves, diacetyl, sodium citrate; monosodium glutamate, disodiuminosine-5'-monophosphate (IMP), disodium guanosine-5-phosphate (GMP); orspecial flavouring substances, water, ethanol, propyleneglycol,glycerine.

The following Examples illustrate the process provided by the presentinvention:

EXAMPLE 1

8.66 g (0.0429 mol) of azidocarboxylic acid diisopropyl ester aredissolved in 40 ml of chloroform. There are then added dropwise 6 g(0.0429 mol) of 2-(2-pyrazinylethyl)-mercaptan and thereafter 4 drops ofconcentrated sulphuric acid. The mixture is held at reflux temperaturefor 4 hours. The mixture is then left to cool to room temperature,treated with 20 ml of saturated sodium bicarbonate solution and theresulting mixture extracted four times with 50 ml of chloroform eachtime. The organic phases are combined, dried over anhydrous sodiumsulphate and concentrated on a rotary evaporator at 40° C./12 mm Hg. Theyield of crudeN-[1'-thia-3'-pyrazin-2-yl-propyl]-N,N'-diisopropoxycarbonylhydrazineamounts to 16.6 g. The product has the following analytical data:

NMR(CDCl₃): 8.60-833 (m, 3H), 6.60 (s, broad, 1H), 5.22 (septet, J =6Hz, 1H) 4.96 (septet, J = 6Hz, 1H), 3.15 (s, 4H), 1.43 (d,J = 6Hz, 6H),1.27 (d, J = 6Hz, 6H), ppm. IR (liq.): bands inter alia at 3350, 1730,1240, 1105, 755 cm⁻¹.

The aforementioned hydrazine derivative is dissolved in 160 ml ofisopropanol and treated with 7.5 g (1.2 mol equivalents) ofdiisopropylethylamine. The mixture is then cooled to 0° C. and excessmethylmercaptan is passed through. After completion of the addition, themixture is stirred for a further 2 hours. The mixture is extracted with50 ml of saturated sodium bicarbonate solution and four times with 100ml of chloroform each time. The combined organic phases are dried overanhydrous sodium sulphate and concentrated on a rotary evaporator at 40°C./12 mm Hg. The crude product obtained is chromatographed on a columnof 150 g of silica gel using hexane/ether (1:4) for the elution. Thefractions are combined and subjected to a short-path distillation in abulb-tube. In this manner there are obtained 1.2 g of pure2-(2-pyrazinylethyl)-methyl-disulphide. n_(D) ²⁰ = 1.5863; boiling point85°-95°/0.035 mm Hg. IR (liq.): bands inter alia at 1520, 1470, 1430,1400, 1300, 1160, 1110, 1060, 1020, 850, 830 cm⁻¹. Odour and flavour:sulphur-like, meaty, vegetable-like, (leek, chive, garlic, onions,cauliflower).

EXAMPLE 2

To 120 ml of diethyl ether, pre-cooled to 0° C., are added whilestirring 3 ml of bromine and thereafter, under an argon atmosphere, 22.5g (0.0696 mol) of crystalline lead rhodanide. The mixture is stirreduntil the colour of the bromine has disappeared completely, thisrequiring 2 hours. The mixture is then filtered from the lead salt andthe filtrate cooled to -5° C. 7.0 g (0.05 mol) of2-(2-pyrazinylethyl)-mercaptan dissolved in 30 ml of ether is added tothe filtrate. After completion of the addition, the mixture is stirredfor 15 minutes at 0° C. to -5° C., then poured on to ice and extractedfour times with 50 ml of ether each time. The organic phases arecombined, washed with 50 ml of water, dried over anhydrous sodiumsulphate and concentrated on a rotary evaporator at 0°-20° C./12 mm Hg.The thus-obtained crude 2-(2-pyrazinyl)-ethylthiorhodanide (12 g) isimmediately further processed. [IR bands (liq.) of the crude product2080 cm⁻¹ ].

Methylmercaptan is passed into 60 ml of freshly distilleddimethoxyethane cooled to -20° C. 27.5 ml (110% relative to mercaptan)of a 2.8% n-butyllithium/hexane solution are added dropwise thereto, awhite suspension forming. 12 g of the foregoing rhodanide dissolved in50 ml of dimethoxyethane are now added dropwise at -20° C. to -30° C.The mixture is left to come to room temperature. The mixture is pouredon to ice and extracted four times with 125 ml of ether each time. Theorganic phases are combined, dried over anhydrous sodium sulphate andconcentrated on a rotary evaporator at 40° C./12 mm Hg. The crudeproduct is chromatographed on 150 g of silica gel using hexane/ether(1:4) for the elution. The fractions are concentrated and subjected to ashort-path distillation in a bulb-type at 90°-92°/0.03 mm Hg. In thismanner there are obtained 2.5 g (26.9% relative to the mercaptan used)of pure 2 -(2-pyrazinylethyl)-methyl-disulphide. n_(D) ²⁰ = 1.5905.

EXAMPLE 3

(a) A solution of 8.15 g (0.055 mol) of trimethyloxoniumtetrafluoroborate in 20 ml of nitromethane is added to a solution,cooled to 0° C., of 5.17 g (0.055 mol) of freshly distilleddimethyldisulphide in 10 ml of nitromethane. After completion of theaddition, the mixture is stirred at this temperature for 90 minutes.There is now added dropwise thereto at 0° C. a solution of 7 g (0.05mol) of 2-(2-pyrazinethyl)-mercaptan as well as 6.45 g (0.05 mol) ofdiisopropylamine in 10 ml of nitromethane. The mixture is left to cometo room temperature, treated with 50 ml of saturated sodium bicarbonatesolution and ice and the mixture extracted four times with 100 ml ofchloroform each time. The organic phases are combined, dried overanhydrous sodium sulphate and then concentrated on a rotary evaporatorat 40° C./12 mm Hg. The crude product obtained is chromatographed on 150g of silica gel using hexane/ether (1:4) for the elution. The fractionsare combined and subjected to a short-path distillation in a bulb-tubeat 85°-88° C./0.03 mm Hg. There are obtained 4.25 g (45.7%) of pure2-(2-pyrazinethyl)-methyl-disulphide.

According to the same procedure, from dimethyldisulphide and1-(2-thiazolyl)-2-methylpropyl-mercaptan there is obtained[1-(2-thiazolyl)-2-methylpropyl]-methyl-disulphide. n_(D) ²⁰ = 1.5770.IR (liq.): bands inter alia at 1500, 1470, 1430, 1420, 1390, 1370, 1195,1140, 1055, 730 cm⁻¹. Odour and flavour: earthy, fruity (cassis),sulphur-like, vegetable-like (celery).

From dimethyldisulphide and 2-mercapto-pyridine there is obtained2-pyridyl-methyl-disulphide. n_(D) ²⁰ = 1.6225. IR (liq.): bands interalia at 1580, 1570, 1450, 1420, 1125, 770 730 cm⁻¹.

Odour and flavour: earthy, sulphur-like, green, vegetable-like(cauliflower, onion), after broad-leaved garlic, cheese.

From dimethyldisulphide and 2-mercapto-thiazole there is obtained2-thiazolyl-methyl-disulphide. n_(D) ²⁰ = 1.6408. IR (liq.): bands interalia at 1485, 1390, 1310, 1060, 1050, 725 cm⁻¹.

Odour and flavour: roast note, sulphur-like, green, cabbage-,chive-like, meat-like (pork).

From dimethyldisulphide and 2-mercapto-pyrimidine there is obtained2-pyrimidinyl-methyl-disulphide. n_(D) ²⁰ = 1.6620. IR (liq.): bandsinter alia at 1560, 1385, 1200, 1175, 785 cm⁻¹.

Odour and flavour: earthy, spicy, vegetable-like (cauliflower,kohlrabi), of cheese.

From dimethyldisulphide and 4,5-dimethyl-2-thiono-4-oxazoline there isobtained (4,5-dimethyl-2-oxazolyl)-methyl-disulphide. n_(D) ²⁰ = 1.5598.IR (liq.): bands inter alia at 2950, 1638, 1495, 1435, 1225, 1175, 1103,950, 745 cm⁻¹.

Odour: spicy "Maggi". Flavour: spicy, chive-like, reminiscent of lightlyfried mushrooms.

(b) A solution of 4.18 g (0.022 mol) of triethyloxoniumtetrafluoroborate in 12 ml of nitromethane is added to a solution of2.86 g (0.022 mol) of diethyldisulphide in 8 ml of nitromethane(filtered over basic aluminum oxide) at reflux temperature. Aftercompletion of the addition, the mixture is stirred at 30°-40° C. for afurther 2 hours. There is then added dropwise at 30° C. a mixture (twophases) of 2.22 g (0.02 mol) of 2-mercapto-pyridine and 2.58 g (0.02mol) of diisopropylethylamine in 15 ml of nitromethane and the resultingmixture is stirred at ca 30°-40° C. for a further 2 hours.

The working-up is carried out as described in Example 3a). There areobtained 2.29 g (67% relative to 2-mercapto-pyridine) of pure2-pyridyl-ethyl-disulphide. n_(D) ²⁰ = 1.6059. IR (liq.): bands interalia at 1580, 1570, 1455, 1424, 1125, 775, 730 cm⁻¹.

Odour: sulphur-like, after onions, penetrating. Flavour: onion-like,sulphur-like, burning.

(c) From 3.3 g (0.022 mol) of dipropyldisulphide, 3.26 g (0.022 mol) oftrimethyloxonium tetrafluoroborate, 2.22 g (0.02 mol) of2-mercapto-pyridine and 2.58 g (0.02 mol) of diisopropylethylamine thereis obtained, according to the procedure described in Example 3b),2-pyridyl-propyl-disulphide. Yield: 2.65 g (71.6% relative to2-mercapto-pyridine). n_(D) ²⁰ = 1.5916. IR (liq.): bands inter alia at1580, 1570, 1450, 1420, 1125, 770, 730 cm⁻¹.

Odour: penetrating, sulphur-like, green, after chive.

Flavour: sulphur-like, green, of chive.

(d) From 3.3 g(0.022 mol) of diisopropyldisulphide, 3.26 g (0.022 mol)of trimethyloxonium tetrafluoroborate, 2.24 g (0.02 mol) of2-mercapto-pyrimidine and 2.58 g (0.02 mol) of diisopropyl-ethylaminethere is obtained, according to the procedure described in Example 3b),2-pyrimidinyl-isopropyl-disulphide. Yield: 2.5 g (67.2% relative to2-mercapto-pyrimidine). n_(D) ²⁰ = 1.5858. IR (liq.): bands inter aliaat 1570, 1560, 1485, 1200, 1175, 1165, 1060, 785, 755 cm⁻¹.

Odour: penetrating, sharp, green, of onions.

Flavour: penetrating, burning, of onions.

(e) From 2.08 g (0.022 mol) of dimethyldisulphide, 4.18 g (0.022 mol) oftriethyloxonium tetrafluoroborate, 2.24 g (0.02 mol) of2-mercapto-pyrimidine and 2.58 g (0.02 mol) of diisopropyl-ethylaminethere is obtained, according to the procedure described in Example (3b),2-pyrimidinyl-methyl-disulphide:

Yield 1.8 g (57% relative to 2-mercapto-pyrimidine). n_(D) ²⁰ = 1.6218.

IR (liq.): bands inter alia at 1560, 1385, 1200, 1175, 785 cm⁻¹.

(f) From 2.68 g (0.022 mol) of diethyldisulphide, 3.26 g (0.022 mol) oftrimethyloxonium tetrafluoroborate, 2.24 g (0.02 mol) of2-mercapto-pyrimidine and 2.58 g (0.02 mol) of diisopropyl-ethylaminethere is obtained, according to the procedure described in Example (3b),2-pyrimidinyl-ethyl-disulphide.

Yield: 2.2 g (64% relative to 2-mercapto-pyrimidine). n_(D) ²⁰ = 1.6025.IR (liq.): bands inter alia at 1570, 1555, 1385, 1200, 1175, 785, 755cm⁻¹.

Odour: sulphur-like, of vegetables (boiled onions).

Flavour: sulphur-like, reminiscent of boiled onions.

EXAMPLE 4

5.65 g (0.483 mol) of 2-mercapto-thiazole and 10 g (0.483 mol) ofN-ethylthiophthalimide are stirred at room temperature in 60 ml ofbenzene for 60 hours. The product is then filtered through paper andsubsequently filtered over 15 g of silica gel. Upon concentration thereis obtained a reddish-yellow product which is still liquid. High-vacuumdistillation through a Vigreux column gives 6.65 g (75%) of a yellowishcoloured product having the following data: boiling point 65°-66°C./0.03 mm Hg; n_(D) ²⁰ = 1.6190. This product is2-thiazolyl-ethyl-disulphide having a purity of 95%. IR (liq.): bands at3120, 3000, 1485, 1390, 1260, 1155, 1060, 1040, 755, 725 cm⁻¹.

Odour and flavour: sulphur-like, roast-like, meat-like, vegetable-like(leek, onions, cabbage), of carrots.

According to the same procedure, from 1-methyl-2-mercapto-imidazole andN-ethylthiophthalimide there is obtained2-(1-methylimidazolyl)-ethyl-disulphide. n_(D) ²⁰ = 1.5890. IR (liq.):bands at 3150, 3000, 1610, 1460, 1415, 1285, 1125, 920, 760, 695 cm⁻¹.

Odour and flavour: sulphur-like, roast-like, vegetable-like (leek,onions), of boiled eggs.

From 2-mercapto-thiazole and N-butylthiophthalimide there is obtained2-thiazolyl-butyl-disulphide. n_(D) ²⁰ = 1.5890. IR (liq.): bands at3120, 3000, 1485, 1390, 1310, 1060, 1045, 725 cm⁻¹.

Odour and flavour: sulphur-like, faintly green, spicy (garlic), sweet,vegetable-like (leek, onions, celery, chive),

From 1-methyl-2-mercapto-imidazole and N-isopropylthiophthalimide thereis obtained 2-(1-methylimidazolyl)-isopropyl-disulphide. n_(D) ²⁰ =1.5736. IR (liq.): bands inter alia at 3130, 3000, 1505, 1455, 1285,1015, 760, 695 cm⁻¹.

Odour and flavour: meat-like, roast-like, spicy, of onions, eggs.

Starting from thenylmercaptan and N-ethylthiophthalimide there isobtained ethyl-thenyl-disulphide. n_(D) ²⁰ = 1.6044. IR (liq.): bandsinter alia at 3000, 1450, 1250, 1035, 850, 700 cm⁻¹.

Odour: penetrating, spicy, after garlic.

Flavour: spicy, of garlic.

Starting from thenylmercaptan and N-propylthiophthalimide there isobtained propyl-thenyl-disulphide. IR (liq.): bands inter alia at 2990,1455, 1220, 1030, 850, 700 cm⁻¹.

Odour: spicy, green (chive).

Flavour: faintly spicy, earthy, green.

Starting from 1-methyl-2-mercapto-imidazole and N-propylthiophthalimidethere is obtained 2-(1-methyl-imidazolyl)-propyl-disulphide. n_(D) ²⁰ =1.5756. IR (liq.): bands inter alia at 3105, 2980, 1500, 1450, 1275,1115, 1010, 750, 685 cm⁻¹.

Odour: sulphur-like, green, vegetable-like.

Flavour: sulphur-like, vegetable-like.

Starting from 2-mercapto-thiazole and N-isopropylthiophthalimide thereis obtained 2-thiazolyl-isopropyl-disulphide. n_(D) ²⁰ = 1.5984. IR(liq.): bands inter alia at 3010, 1490, 1395, 1160, 1065, 1050, 730cm⁻¹.

Odour: sulphur-like, faint roast note.

Flavour: sulphur-like, faint roast-note, burning.

Starting from 1-methyl-2-mercaptomethyl-pyrrole andN-ethylthiophthalimide there is obtained(1-methyl-2-pyrrolyl)-methyl-ethyl-disulphide. n_(D) ²⁰ = 1.5816. IR(liq.): bands inter alia at 3140, 3000, 1495, 1310, 1250, 1090, 720,cm⁻¹.

Odour: sweetish, green, sulphur-like (onion-like).

Flavour: sulphur-like (onion-like), sweet.

Starting from 4,5-dimethyl-2-thiono-4-oxazoline andN-ethylthiophthalimide there is obtained(4,5-dimethyl-2-oxazolyl)ethyl-disulphide. n_(D) ²⁰ = 1.5467. IR (liq.):bands inter alia at 3020, 2970, 1640, 1450, 1175, 1105, 950, 745 cm⁻¹.

Odour and flavour: spicy, "Maggi", mushroom-like.

Starting from 4-ethyl-2-thiono-4-oxazoline and N-ethylthiophthalimidethere is obtained (4-ethyl-2-oxazolyl)ethyl-disulphide. n_(D) ²⁰ =1.5549. IR (liq.): bands inter alia at 3000, 2970, 1590, 1485, 1250,1135, 1080, 950, 760 cm⁻¹.

Odour: spicy (lovage), slightly sulphurous, cheese-like.

Flavour: "Maggi", onion-like, reminiscent of fully matured cream cheese.

Starting from 4,5-dimethyl-2-thiono-4-oxazoline andN-propylthiophthalimide there is obtained(4,5-dimethyl-2-oxazolyl)propyl-disulphide. n_(D) ²⁰ = 1.5321. IR(liq.): bands inter alia at 2980, 1635, 1450, 1225, 1173, 1100, 945, 740cm⁻¹.

Odour and flavour: slightly sulphurous, chive-like and broad-leavedgarlic-like.

EXAMPLE 5

A mixture of 8.26 g (0.052 mol) of2-(4-methyl-5-thiazolyl)-ethyl-mercaptan and 33.07 g (0.208 mol) ofdimethyldisulphide is treated with 50 mg of sodium hydride (50%dispersion in oil) and the mixture is heated to reflux for 4 hours. Themixture is then left to cool, filtered over 10 g of aluminium oxide(activity I, neutral), which is back-washed with ether, and concentratedin a vacuum. The resulting crude product (9.5 g) is distilled through aHempel column under a high vacuum, there being obtained 6.45 g of[2-(4-methyl-5-thiazolyl)-ethyl]-methyl-disulphide. Boiling point104°-110°/0.02 mm Hg; n_(D) ²⁰ = 1.5944; purity: 99%. IR (liq.): bandsinter alia at 3100, 2960, 1545, 1415, 1220, 955, 1005, 840, 795 cm⁻¹.

Odour: sulphur-like, spicy (mustard).

Flavour: sulphur-like, spicy, hot.

EXAMPLE 6

(a) 8 g (0.058 mol) of phenethylmercaptan are added with intensivestirring to a suspension of 12 g (0.058 mol) of N-ethylthiophthalimidein 70 ml of benzene. After a few minutes, a homogeneous solution formsand the phthalimide slowly begins to precipitate out therefrom. Afterstirring for 48 hours at room temperature, the mixture is filteredthrough a paper filter, the filtrate is concentrated in a vacuum and thecrude 2-phenylethyl-ethyl-disulphide (12.8 g) obtained is distilledthrough a Vigreux column. There are thus obtained 10.5 g of pure product(91% of theory) which has a purity of 99% (gas-chromatographicestimation). Boiling point 87-88 mm Hg/0.04 mm Hg; n_(D) ²⁰ = 1.5742. IR(liquid): bands inter alia at 3020, 1610, 1505, 1460, 1260, 710 cm⁻¹.

Odour: sulphur-like, spicy, sweetish.

Flavour: spicy, sweetish, somewhat sulphur-like.

(b) Starting from 5 g (0.033 mol) of 3-phenylpropyl-mercaptan and 6.65 g(0.033 mol) of N-ethylthiophthalimide there are obtained, according tothe procedure described in Example 6a) and after distillation, 4.85 g of3-phenylpropyl-ethyl-disulphide (purity 98%). Boiling point 90°-91°/0.04mm Hg; n_(D) ²⁰ = 1.5639. IR (liquid): bands inter alia at 3080, 2980,1950, 1605, 1700, 1455, 1250, 845, 805 cm⁻¹.

Odour: sulphur-like, green, vegetable-like;

Flavour: vegetable-like, sulphur-like, green.

(c) Starting from 5 g (0.028 mol) of 5-phenylpentyl-mercaptan and 5.62 g(0.028 mol) of N-ethylthiophthalimide there are obtained, according tothe procedure described in Example 6a) and after filtration throughsilica gel (back-washing with hexane) and bulb-tube distillation, 2.98 gof 5-phenylpentyl-ethyl-disulphide (purity: 99%). Boiling point:150°-180° C. (oven temperature)/0.02 mm Hg; n_(D) ²⁰ = 1.5512. IR(liquid): bands inter alia at 2930, 1950, 1600, 1590, 1445, 1250, 1025,840, 795 cm⁻¹.

Odour: sulphur-like, green, flowery;

Flavour: flowery, green.

(d) Starting from 5.6 g (0.048 mol) of 2-furylethyl-mercaptan and 9.1 g(0.048 mol) of N-ethylthiophthalimide there are obtained, according tothe procedure described in Example 6a) and after chromatography on 100 gof silica gel (elution with toluene), 2.38 g ofethyl-2-(2-furyl)-ethyl-disulphide (purity: 96%). n_(D) ²⁰ = 1.5450. IR(liquid): bands inter alia at 3000, 1600, 1505, 1150, 1010, 735 cm⁻¹.

Odour: sulphur-like, penetrating, after onions;

Flavour: sulphur-like, green, faintly flowery.

The following Examples illustrate typical odorant and/or flavouringcompositions provided by the present invention:

EXAMPLE 7

A broth can be prepared as follows:

    ______________________________________                                         A) 20.0 g in each case of a mixture A or B                                                        A      B                                                                      Parts by weight                                          ______________________________________                                        2-Pyrimidinyl-methyl-disulphide                                                                      --       0.5                                           Diallyldisulphide      60       60                                            Allylmercaptan         0.5      0.5                                           Mustard oil synthetic  2.5      2.5                                           Dimethyldisulphide     0.5      --                                            2,4-Decadienal (10% in ethyl alcohol)                                                                1        1                                             Capric aldehyde        0.1      0.1                                           Maltol                 2.5      2.5                                           Butyric acid (10% in ethyl alcohol)                                                                  0.2      0.2                                           Benzyl alcohol         132.7    132.7                                                                200.0    200.0                                         ______________________________________                                    

are mixed with 1000 g of onion oil. At an amount of 20 g/100 l of broththe odour and flavour of the broth prepared using composition A areinsipid, whereas the broth prepared using composition B possesses anexcellent onion flavour.

    ______________________________________                                         B) 20.0 g in each case of a mixture A or B                                                        A      B                                                                      Parts by weight                                          ______________________________________                                        2(1-Methylimidazolyl)-ethyl-disulphide                                                               --       20                                            Diallyldisulphide      60       40                                            Allylmercaptan         0.5      0.5                                           Mustard oil synthetic  2.5      2.5                                           Dimethyldisulphide     0.5      0.5                                           2,4 Decadienal (10% in ethyl alcohol)                                                                1.0      1.0                                           Capric aldehyde        0.1      0.1                                           Maltol                 2.5      2.5                                           Butyric acid (10% in ethyl alcohol)                                                                  0.2      0.2                                           Benzyl alcohol         132.7    132.7                                                                200.0    200.0                                         ______________________________________                                    

are mixed with 1000 g of onion oil. At an amount of 20 g/100 l of broththe broth aromatised with composition A, a traditional aromacomposition, possesses a metallic after-flavour as well as anunsatisfactory onion note. By the partial replacement of thediallyldisulphide by 2-(1-methylimidazolyl)-ethyl-disulphide(composition B) the aromatised broth takes on an agreeable sweetish notereminiscent of boiled onions.

    ______________________________________                                         C) 20.0 g in each case of a mixture A or B                                                        A      B                                                                      Parts by weight                                          ______________________________________                                        2-Pyridyl-ethyl-disulhide                                                                            --       0.5                                           Diallyldisulphide      60       60                                            Mustard oil synthetic  2.5      2.5                                           Dimethyldisulphide     0.5      --                                            Methylthiopropionic acid methyl ester                                                                0.5      0.5                                           Leaf alcohol           2.0      2.0                                           Diacetyl (10% in ethanol)                                                                            0.2      0.2                                           Maltol                 2.0      2.0                                           Benzyl alcohol         132.3    132.3                                                                200.0    200.0                                         ______________________________________                                    

are mixed with 1000 g of onion oil. At an amount of 20 g/100 l of broththe odour and flavour of the broth prepared by using the composition Aare insipid. The broth prepared using composition B possesses anexcellent onion flavour. It is reminiscent of fresh onions, a faintlyhot-burning note being noticed.

    ______________________________________                                         D) 20.0 g in each case of a mixture A or B                                                        A      B                                                                      Parts by weight                                          ______________________________________                                        2-Pyrimidinyl-ethyl-disulphide                                                                       --       0.5                                           Diallyldisulphide      60       60                                            Mustard oil synthetic  2.5      2.5                                           Dimethyldisulphide     0.5      --                                            Methylthiopropionic acid methyl ester                                                                0.5      0.5                                           Leaf alcohol           2.0      2.0                                           Diacetyl (10% in ethanol)                                                                            0.2      0.2                                           Maltol                 2.0      2.0                                           Benzyl alcohol         132.3    132.3                                                                200.0    200.0                                         ______________________________________                                    

are mixed with 1000 g of onion oil. At an amount of 20 g/100 l of broththe odour and flavour of the broth prepared using composition A areinsipid. Upon replacement of the dimethyldisulphide by2-pyrimidinyl-ethyl-disulphide the onion flavour of the broth isadvantageously altered with the same dosage of composition B, in that afaintly hot-burning note reminiscent of fresh onions sets in.

EXAMPLE 8

A brown meat sauce can be obtained as follows: 125.0 g of a mixtureconsisting of

    ______________________________________                                                               Parts by weight                                        ______________________________________                                        Cooking salt             8.00                                                 Monosodium glutamate     2.67                                                 Sugar                    4.00                                                 HVP, Type 4 BE (hydrolysed vegetable proteins)                                                         6.40                                                 Onion powder             1.84                                                 Caramel powder           1.12                                                 Tomato powder            5.33                                                 VEE-Cream (artificial cream on the basis                                        of vegetable oils, spray dried)                                                                      26.67                                                Laurel, soluble          0.04                                                 White pepper, soluble    0.08                                                 Thyme, soluble           0.04                                                 Marjoram, soluble        0.04                                                 Nutmeg, soluble          0.04                                                 Modified waxy maize corn starch (maize starch)                                                         18.67                                                White flour              25.06                                                                         100.00                                               ______________________________________                                    

are stirred into 1 liter of cold water and boiled up while stirringcontinuously. After boiling for 3 minutes, the flavour of this brownmeat sauce is initially insipid and not typical. After the addition of 2ppm of 2-thiazolyl-methyl-disulphide, there is established an excellentmeat flavour with a distinct roast onion-like, meat-like note.

EXAMPLE 9

An onion cream soup can be obtained as follows:

    ______________________________________                                         A) 140.0 g of a mixture consisting of                                                            Parts by weight                                           ______________________________________                                        Margarine             28.70                                                   White flour           18.61                                                   Dried onions          12.52                                                   Skim milk powder      12.52                                                   Carrot starch         12.52                                                   Onion powder          3.75                                                    Cooking salt          8.75                                                    Monosodium glutamate  1.25                                                    HVP (hydrolysed vegetable proteins)                                                                 1.25                                                    White pepper, milled  0.13                                                                          100.00                                                  ______________________________________                                    

are added to 1 liter of cold water, boild up and removed from the heatas soon as the pieces of onion are cooked. The flavour of this onionsoup is insipid, not pronounced, and the flavour scarcely comes intoplay. By the addition of 2 ppm of[1-(2-thiazolyl-2-methylpropyl)]-methyldisulphide the onion flavourpresent is enhanced in an advantageous manner. In addition, the souptakes on an agreeable vegetable-like, spicy note which is reminiscent ofcelery.

    ______________________________________                                         B) 140.0 g of a mixture consisting of                                                            Parts by weight                                           ______________________________________                                        Margarine             28.70                                                   White flour           18.61                                                   Dried onions          12.52                                                   Skim milk powder      12.52                                                   Carrot starch         12.52                                                   Onion powder          3.75                                                    Cooking salt          8.75                                                    Monosodium glutamate  1.25                                                    HVP (hydrolysed vegetable proteins)                                                                 1.25                                                    White pepper, milled  0.13                                                                          100.00                                                  ______________________________________                                    

are added to 1 liter of cold water, boiled up and removed from the heatas soon as the pieces of onion are cooked. The flavour of this onionsoup is insipid, not very pronounced and the flavour comes into playonly faintly. By the addition of 0.5 ppm of 2-thiazolyl-ethyl-disulphidethe existing onion flavour is enhanced in an extremely advantageousmanner in that a pronounced, pleasant roast onion note and a faint brothnote appears.

EXAMPLE 10

A clear meat soup can be obtained as follows: 20.0 g of a mixtureconsisting of

    ______________________________________                                                               Parts by weight                                        ______________________________________                                        Cooking salt             50.00                                                Monosodium glutamate     20.04                                                Caramel powder           0.20                                                 Nutmeg, soluble          0.06                                                 Clove, soluble           0.06                                                 Coriander, soluble       0.08                                                 White pepper, soluble    0.06                                                 HVP, Type 3 H1 (hydrolysed vegetable proteins)                                                         8.90                                                 HVP, Type RF-B (hydrolysed vegetable proteins)                                                         2.60                                                 Vegetable fat, melting point 40° C                                                              17.00                                                Roast onion powder       1.00                                                                          100.00                                               ______________________________________                                    

are added to 1 liter of hot water. The flavour of this clear meat soupis initially unsatisfactory (faint meat and onion flavour).

(a) By the addition of 3-5 ppm of 2-(2-pyrazinylethyl)-methyl-disulphidethe meat and onion flavour are enhanced in an extremely advantageousmanner.

(b) By the addition of 3-5 ppm of 2-pyridyl-propyl-disulphide the meataroma is enhanced in an advantageous manner in that there now appears aspicy-green note which is reminiscent of chive and which harmonises wellwith the meat flavour.

EXAMPLE 11

A clear meat broth can be obtained as follows: 20.0 g of a mixtureconsisting of:

    ______________________________________                                                             Parts by weight                                          ______________________________________                                        Salt                   45.0                                                   Sodium glutamate       20.0                                                   Sugar                  2.4                                                    Hydrolysed vegetable protein                                                  (e.g. HVP, Type 4BE and Type 245)                                                                    14.0                                                   Celery powder          1.6                                                    Onion powder           1.6                                                    Garlic powder          0.6                                                    Curcuma powder         0.3                                                    Pepper powder, white   0.1                                                    Potato starch          4.4                                                    Vegetable fat (melting point 40° C)                                                           10.0                                                                          100.0                                                  ______________________________________                                    

are added to 1 liter of hot water. The flavour of this soup is insipid,weak and not convincing. By the addition of 3-5 ppm of(4,5-dimethyl-2-oxazolyl)-ethyl-disulphide, the weak meat flavourpresent is significantly strengthened, a pleasant, spicy notereminiscent of roast onions also being obtained, which harmonisesexcellently with the meat flavour present.

EXAMPLE 12

A meat broth can be obtained as follows: 18.0 g of a mixture consistingof

    ______________________________________                                                               Parts by weight                                        ______________________________________                                        Cooking salt             45                                                   Monosodium glutamate     20                                                   Sugar                    2.4                                                  HVP, Type 4 BE (hydrolysed vegetable                                          proteins)                5.6                                                  HVP, Type 245 (hydrolysed vegetable proteins)                                                          8.4                                                  Celery powder            1.6                                                  Onion powder             2.2                                                  White pepper             0.4                                                  Carrot starch            4.4                                                  Hardened vegetable oil   10                                                                            100.0                                                ______________________________________                                    

are added to 1 liter of hot water. The flavour of this meat broth isinsipid and not pronounced. By the addition of 2 ppm of2-(1-methylimidazolyl)-isopropyl-disulphide the meat flavour is enhancedin an advantageous manner. In addition to the pronounced meat note, thethus-obtained meat broth also possesses a pleasant vegetable-like note.

EXAMPLE 13

An exotic fruit flavour can have the composition A or B:

    ______________________________________                                                             A      B                                                                      Parts by weight                                          ______________________________________                                        2-Thiazolyl-butyl-disulphide                                                                         --       1.5                                           Propylmercaptan (10% in ethyl alcohol)                                                               2.5      1.0                                           Leaf alcohol (10% in ethyl alcohol)                                                                  1        1                                             α-Pinene         5        5                                             Isobutyric acid linalyl ester                                                                        5        5                                             Acetic acid amyl ester 7        7                                             Propionic acid geranyl ester                                                                         10       10                                            Aldehyde C 16          12       12                                            Aldehyde C 18 (10% in ethyl alcohol)                                                                 3        3                                             Maltol (2% in ethyl alcohol)                                                                         4        4                                             Aldehyde C 14          25       25                                            Garlic oil (0.5% in ethyl alcohol)                                                                   250      250                                           Propyleneglycol        670.5    670.5                                                                1000.0   1000.0                                        ______________________________________                                    

The partial replacement of the propylmercaptan by2-thiazolyl-butyl-disulphide (composition B) produces a very typical,fruity, sweetish note which is strongly reminiscent of the durian fruit.

EXAMPLE 14

A vegetable flavour can have the composition A or B:

    ______________________________________                                                             A      B                                                                      Parts by weight                                          ______________________________________                                        2-Pyridyl-methyl-disulphide                                                                          --       5                                             Methylchavicol (1% in ethyl alcohol)                                                                 0.5      0.5                                           Garlic oil             2.0      2.0                                           Thymol (1% in ethyl alcohol)                                                                         0.5      0.5                                           Isobutyric acid piperonyl ester (1% in                                          ethyl alcohol)       3        3                                             Nona-2,6-dienal (1% in ethyl alcohol)                                                                5        5                                             Acetic acid linalyl ester (1% in ethyl                                          alcohol)             5        5                                             3-Hexenyl-acetylacetate                                                                              10       10                                            Ethanol                974      969                                                                  1000     1000                                          ______________________________________                                    

The presence of 2-pyridyl-methyl-disulphide in composition B enhancesthe vegetable-like note which is now strongly reminiscent of fresh,green beans.

EXAMPLE 15

A vegetable flavour can have the composition A or B:

    ______________________________________                                                             A      B                                                                      Parts by weight                                          ______________________________________                                        2-(1-Methyl-2-imidazolyl)-propyl-                                             disulphide (10% in ethanol)                                                                          --       10.0                                          Garlic oil (1%o in ethanol)                                                                          2.0      2.0                                           Thymol (1%o in ethanol)                                                                              0.5      0.5                                           Isobutyric acid piperonyl ester (1%o                                          in ethanol)            3.0      3.0                                           Acetic acid linalyl ester (1% in ethanol)                                                            5.0      5.0                                           3-Hexenyl-acetylacetate                                                                              8.0      8.0                                           Methional              2.0      2.0                                           Ethanol                979.5    969.5                                                                1000.0   1000.0                                        ______________________________________                                    

The odour of the traditional composition A is inferior to the odour ofcomposition B. The addition of2-(1-methyl-2-imidazolyl)-propyl-disulphide gives a distinctly enhanced,vegetable-like, green note which is reminiscent of fresh green beans.

EXAMPLE 16

An onion flavour can have the composition A or B:

    ______________________________________                                                          A       B                                                                     Parts by weight                                             ______________________________________                                        2-Pyrimidinyl-ethyl-disulphide                                                                    --        4.0                                             Onion oil           2.0       2.0                                             Onion powder        400.0     400.0                                           Maltodextrin (in powder form)                                                                     598.0     594.0                                                               1000.0    1000.0                                          ______________________________________                                    

The odour and flavour of an onion powder prepared with composition A areinsipid in comparison with an onion powder prepared with composition B.By the addition of 2-pyrimidinyl-ethyl-disulphide the odour and flavourof the onion powder are strongly improved. There appears a distinct,very pleasant novel note in the foreground which is strongly reminiscentof boiled onions.

EXAMPLE 17

An onion flavour can have the composition A or B:

    ______________________________________                                                          A       B                                                                     Parts by weight                                             ______________________________________                                        2-Phenylethyl-ethyl-disulphide                                                  (0.1% in ethanol) --        0.5                                             Onion oil           1.0       1.0                                             Ethanol             10.0      10.0                                            Migliol (neutral oil)                                                                             989.0     988.5                                                               1000.0    1000.0                                          ______________________________________                                    

The comparison of the traditionally insipid flavour A with the novelcomposition B indicates that the presence of2-phenylethyl-ethyl-disulphide (composition B) brings about anappreciably enhanced improvement. The impression of boiled onions isonly present in composition B.

EXAMPLE 18

An onion flavour can have the composition A or B:

    ______________________________________                                                           A       B                                                                     Parts by weight                                            ______________________________________                                        (1-Methyl-2-pyrrolyl)-methyl-ethyl-                                           disulhide (10% in ethanol)                                                                         --        5                                              Onion oil            20        20                                             Ethanol              980       975                                                                 1000      1000                                           ______________________________________                                    

The odour of the traditional composition A is inferior to that ofcomposition B. By the addition of(1-methyl-2-pyrrolyl)-methyl-ethyl-disulphide the odour is stronglyimproved. The note reminiscent of boiled onions only appears distinctlyin composition B.

EXAMPLE 19

A soya flavour can have the composition A or B:

    ______________________________________                                                           A       B                                                                     Parts by weight                                            ______________________________________                                        3-Phenylpropyl-ethyl-disulphide                                                                    --        5                                              2,4-Decadienal (10% in ethanol)                                                                    0.8       0.8                                            2-Hexenal            10        10                                             Caproic aldehyde     20        20                                             Dimethylsulphide     20        15                                             Methional            40        40                                             Piperidine           60        60                                             Ethanol              849.2     849.2                                                               1000.0    1000.0                                         ______________________________________                                    

A comparison of A and B indicates that the traditional composition Afalls off odour-wise and flavour-wise. By the partial replacement of thedimethylsulphide by 3-phenylpropyl-ethyl-disulphide there appears a notereminiscent of soya which is very strong in the foreground.

EXAMPLE 20

    ______________________________________                                        Mustard flavours (A and B)                                                                       A       B                                                                     Parts by weight                                            ______________________________________                                        [2-(4-Methyl-5-thiazolyl)-ethyl]-                                             methyldisulphide     --        1                                              Methylchavicol       2         2                                              Eugenol              3         3                                              Mace oil             5         5                                              Thymol (10% in ethanol)                                                                            30        30                                             Mustard oil synthetic                                                                              60        60                                             Ethanol              900       899                                                                 1000      1000                                           ______________________________________                                    

The odour and flavour of the mustard composition A are not verypronounced. On the other hand, by the addition of[2-(4-methyl-5-thiazolyl)-ethyl]-methyl-disulphide (composition B) thespicy character is enhanced in an advantageous manner. Moreover, thereappears a hot note which is desirable for mustard.

EXAMPLE 21

A horseradish flavour can have the composition A or B:

    ______________________________________                                                           A       B                                                                     Parts by weight                                            ______________________________________                                        2-Thiazolyl-isopropyl-disulphide                                                                   --        1.0                                            Acetic acid          0.6       0.6                                            Clove oil            1.0       1.0                                            Mace oil             1.4       1.4                                            1-Acetoxy-2-butyl-ethane                                                                           7.0       7.0                                            Mustard oil synthetic                                                                              30.0      30.0                                           Ethanol              960.0     959.0                                                               1000.0    1000.0                                         ______________________________________                                    

A comparison of composition B with the traditional composition A showsimmediately that the latter falls off strongly. By the addition of2-thiazolyl-isopropyl-disulphide the odour and flavour are substantiallyimproved in that the hot-burning note reminiscent of horseradish appearsmuch stronger in the foreground.

EXAMPLE 22

A garlic flavour can have the composition A or B:

    ______________________________________                                                           A       B                                                                     Parts by weight                                            ______________________________________                                        Ethyl-thenyl-disulphide (0.1% in                                              ethanol)             --        0.5                                            Garlic oil           1.0       1.0                                            Alcohol              10        10                                             Tween 80 (Polyoxyethylene sorbitan                                            monooleate)          30        30                                             Propyleneglycol      30        30                                             Sorbitol             35        35                                             Water                894       893.5                                                               1000.0    1000.0                                         ______________________________________                                    

The odour and flavour of the traditional composition A fall off stronglyin comparison with composition B. By the addition ofethyl-thenyl-disulphide the garlic character is significantly improvedin that the characteristic sulphur-like, spicy note in the foregroundappears only in composition B.

EXAMPLE 23 Mushroom soup (canned soup)

A mixture consisting of:

    ______________________________________                                                            Parts by weight                                           ______________________________________                                        Skim milk powder      35                                                      Margarine             25                                                      White flour           26                                                      Cooking salt          5.5                                                     Dried mushroom pieces 4.5                                                     Natural mushroom aroma                                                                              2.5                                                     Sodium glutamate      1.6                                                     Onion powder          0.8                                                     Sugar                 0.4                                                     Pepper flavour, soluble                                                                             0.4                                                     Clove flavour, soluble                                                                              0.3                                                                           100.0                                                   ______________________________________                                    

is dissolved in water and boiled up in the usual manner. The flavour ofthis soup is slightly typical in relation to the mushroom flavour. Bythe addition of 3-5 ppm of propyl-thenyl-disulphide the mushroom flavourpresent is activated. The soup has a stronger and fresher flavour. Theimpression of the co-use of fresh mushrooms is produced.

EXAMPLE 24

A honey flavour can have the composition A or B:

    ______________________________________                                                           A       B                                                                     Parts by weight                                            ______________________________________                                        5-Phenylpentyl-ethyl-disulphide                                                                    --        2                                              Methylacetophenone   0.5       0.5                                            Geranium oil         0.3       0.3                                            Ethylvanillin        6         6                                              Phenylacetic acid    12        12                                             Pelargonic acid ethyl ester                                                                        30        30                                             Acetic acid amyl ester                                                                             200       200                                            Acetic acid ethyl ester                                                                            100       100                                            Valerianic acid amyl ester                                                                         250       250                                            Ethanol              401.2     399.2                                                               1000.0    1000.0                                         ______________________________________                                    

A comparison of A and B indicates that the traditional composition Afalls off strongly. By the addition 5-phenylpentyl-ethyl-disulphide animprovement in the aroma now appears. The ester note is now suppressedand a weak flowery note, which is strongly reminiscent of floral honey,appears in the foreground.

EXAMPLE 23

An odorant substance composition (flowery note) can have the compositionA or B:

    ______________________________________                                                           A       B                                                                     Parts by weight                                            ______________________________________                                        Ethyl-2-(2-furyl)-ethyl-disulphide                                                                 --        5                                              Methylheptenone      5         5                                              Linalool             5         5                                              Acetic acid linalyl ester                                                                          10        10                                             Citronellol          30        30                                             Geraniol             40        40                                             Ethanol              910       905                                                                 1000      1000                                           ______________________________________                                    

A comparison of A with B shows immediately that the traditionalcomposition A falls off strongly. By the addition ofethyl-2-(2-furyl)-ethyl-disulphide the flowery-green note of thecomposition is enhanced. It is intensively reminiscent of geranium.

What we claim is:
 1. A compound selected from the group consisting of2-thiazolyl-methyl-disulphide, 2-thiazolyl-ethyl-disulphide, 2-thiazolyl-isopropyl-disulphide, 2-thiazolyl-butyl-disulphide, [1-(2-thiazolyl)-2-methylpropyl]-methyl-disulphide and [2-(4-methyl-5-thiazolyl)-ethyl]-methyl-disulphide.
 2. A disulphide according to claim 1 having the formula:2-thiazolyl-methyl-disulphide.
 3. A disulphide according to claim 1 having the formula:2-thiazolyl-ethyl-disulphide.
 4. A disulphide according to claim 1 having the formula:2-thiazolyl-isopropyl-disulphide.
 5. A disulphide according to claim 1 having the formula:2-thiazolyl-butyl-disulphide.
 6. A disulphide according to claim 1 having the formula:[1-(2-thiazolyl)-2-methylpropyl]-methyl-disulphide.
 7. A disulphide according to claim 1 having the formula:[2-(4-methyl-5-thiazolyl)-ethyl]-methyl-disulphide. 